Remove peer_md and use peer_sigalg instead.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2324)
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 74b37e0..ad6ac5f 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -937,10 +937,7 @@
         SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_WRONG_SIGNATURE_TYPE);
         return 0;
     }
-    /*
-     * Store the digest used so applications can retrieve it if they wish.
-     */
-    s->s3->tmp.peer_md = md;
+    /* Store the sigalg the peer uses */
     s->s3->tmp.peer_sigalg = lu;
     return 1;
 }